1. Field of the Invention
The present invention relates to an image forming apparatus with an image reading apparatus, such as a copier or a multi-function printer (MFP).
2. Description of the Related Art
As an apparatus that realizes both image forming onto a recording sheet and reading of an image on an original sheet, an image forming apparatus with an image reading apparatus is available that includes an automatic document feeder unit (ADF) at an upper portion of an image forming apparatus main unit, and in which an image reading unit is disposed that is capable of performing flow reading with respect to original sheet.
An image forming apparatus capable of double-sided printing on a recording sheet includes a double-side-print conveyance path for switching back a recording sheet after completing a process to form an image on a front surface side of the recording sheet, and conveying the recording sheet once again to an image forming unit to form an image on the rear surface side of the recording sheet. A similar operation is also performed in an image reading apparatus that is capable of double-sided reading of an original sheet. In a typical image forming apparatus with an image reading apparatus, a dedicated conveyance path for a recording sheet is provided in an image forming unit, and a dedicated conveyance path for an original sheet is provided in an image reading unit. Further, to enable both double-sided printing and double-sided reading, it is necessary to provide two double-side-print conveyance paths that are used for a recording sheet and an original sheet, respectively, and there is a concern that the size of the apparatus will increase as a result. To solve this problem, Japanese Patent Application Laid-Open No. 2006-232467 discloses a configuration in which a double-side-print conveyance path for a recording sheet also serves as a conveyance path for flow reading of an original-sheet. Further, Japanese Patent Application Laid-Open No. H10-129071 discloses technology that reads an image printed on an original sheet, creates an overwriting image based on the image, and performs overwriting printing onto the original sheet that was read.
Further, according to the configuration disclosed in Japanese Patent Application Laid-Open No. 2006-232467, an operation is described that reads both sides of an original sheet by reading one side of the original sheet and thereafter passing the original sheet directly through an image forming unit without stopping and conveying the original sheet again to an image sensor by a double-side reversing unit of the image forming unit.
Although Japanese Patent Application Laid-Open No. 2006-232467 discloses a configuration in which a double-side-print conveyance path is used for both an original sheet and a recording sheet, an operation for overwriting an image on an original sheet that was read is not discussed therein. According to the configuration disclosed in Japanese Patent Application Laid-Open No. 2006-232467, for example, in a case where operations are performed to read images on both sides of an original sheet and thereafter analyze the two images and, based on the analysis result, decide the contents of image forming or the side of an original sheet on which to perform overwriting printing, the aforementioned operations result in the original sheet passing through the image forming unit a plurality of times including the time of being passed directly therethrough without stopping when performing the double-sided reading and the time of performing the overwriting printing. Therefore, there is a concern that a problem will arise that the original sheet will be affected as a result of passing through the image forming unit or that the image forming unit will become worn as a result of the original sheet passing therethrough a plurality of times.